The aim of the research was to evaluate under greenhouse conditions, the effect of two different levels of soil humidity (20-25% and 50-55%) on the development of Angiosorus solani artificially inoculated in the soil. The twopotato (Solanum tuberosum) varieties, Mirka and Cardinal, were considered as resistant and susceptible to the diseasem, respectively. Water in the soil was adjusted periodically to maintain the soil humidity levels constant during the research. A completely randomized experimental design with five replications and one plant per replication was used. Emergence, days between emergence and harvest, disease symptoms, weight and number of tubers at harvest were evaluated. Results were submitted to variance analysis and Fishers mean difference test. Results indicated that there were no significant differences (P £ 0.05) between treatments for emergence; on average tubers emerged at 12 days after planting. The period from emergence to harvest showed significant differences (P £ 0.05) between humidity levels with the longer period for the higher humidity level (50-55%). The disease was present only in treatments inoculated with A. solani and mainly in the Cardinal variety. Only one Mirka plant developed disease symptoms. It was not observed effect of soil humidity on the development of the disease